[Q] Help rooting omap5 running 4.2.2

As title, I'm trying to root a development board running 4.2.2. I do have root access and put busybox and su, but my problem is that whenever I start apps that require root access, superuser never gives me prompt asking whether root access is allow (yes, my setting in Superuser is to prompt for every apps that require root), as a result, the app would not run reporting that my device is not rooted. As an example, when I trying to run droidvncserver, it would tell me "could not start server", but if I start it as root on a shell, it would run and start server, this leads me to think that droidvncserver is not requesting root access or Superuser does not know that droidvncserver needs root access. I'm pretty sure I'm missing something in my system, but what is it. All this works on a rooted phone, but not on the development board. I've read through some of the rooting script for other phones, mostly include remounting /system as rw and put busybox and su onto the system, and that's what I've done on the board, but there's just no connection between those root-require apps and superuser. Anyone knows what I'm doing wrong/missing?

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